Selective catalytic reduction (SCR) has been widely used in diesel engine applications as an emission-reduction technology with the ability to deliver reduced emissions of nitrogen oxides (NOx). SCR uses a basic chemistry reaction to reduce NOx emissions by using hot exhaust, diesel exhaust fluid (e.g. a urea-water solution) and a catalytic converter. Vaporized diesel exhaust fluid (DEF) and hot exhaust gases enter a catalytic converter located in the exhaust system after the diesel particulate filter. When the DEF is injected into the hot exhaust stream and comes into contact with the SCR catalyst, the ammonia created from the urea reacts with NOx to form nitrogen and water vapor. If the DEF supply fails (e.g. an empty tank), the DEF quality is poor (e.g. an off-nominal DEF supply and/or dilution event), and/or if the SCR system is subjected to malfunction through tampering or component failure or defect, the SCR NOx conversion can degrade or fail to convert an acceptable amount of NOx. While NOx conversion may be degraded or failed, engine operations may otherwise be performing normally (e.g. achieving torque, power, speed, and/or fuel efficiency target values).
A system for incentivizing an operator to correct an SCR maintenance or compliance issue is known for on-road applications. Due to the similarity in operating conditions and accessibility to infrastructure for on-road applications, presently known incentive structures include utilizing a fixed derate type and severity. Furthermore, on-road applications have vehicle sensors that can be used to delay incentive derates until the vehicle speed is below certain threshold. However, certain vehicles and applications lack speed sensors, and SCR aftertreatment systems are employed in a wide variety of off-road and non-vehicular applications. Thus, a fixed derate type of incentive employed for on-road vehicles may provide unsatisfactory results, particularly in other applications. Therefore, there remains a need for additional developments in this technology area.